A bone punch of the type of this class, which is called a surgical punching instrument, is known from DE 20 2004 017 974 U1 (and corresponding U.S. Pat. No. 7,655,020). This prior-art bone punch has a guide shaft, at which a handle is arranged in a fixed manner, which runs angled to the guide shaft. Furthermore, an actuating lever, which is pivotably mounted in this connection area, is provided in the area of transition from the guide shaft to this handle. In this connection area or in the area of the pivotable mounting of the actuating lever, the connection area forms two side walls, which are spaced apart from one another, between which the actuating lever protrudes through with an adjusting lever and extends on the top over the planar guiding surface of the guide shaft in the normal operating state.
In this connection, this adjusting lever of the actuating lever operatively interacts with a recess of a punching slide, which is open downwards toward the guide shaft. The punching slide has a “lower” sliding surface toward the punching slide, with which the punching slide is arranged longitudinally displaceably on the guide shaft. Guide elements, which have a T-shaped profile and engage one another in a positive-locking manner, are provided for the secure hold of the punching slide on the guide shaft. Because of a special configuration of the mounting of the actuating lever between the two side walls the actuating lever can be “retracted” from its active position with its adjusting lever engaging with the punching slide, so that the adjusting lever no longer operatively interacts with the punching slide. In this “retracted” position of the actuating lever the punching slide can be returned distally along the guide shaft until the guide elements of the punching slide and of the guide shaft become disengaged. In this position, the punching slide can thus be completely removed from the guide shaft in a simple manner, since there is no longer any connection between these parts. The guide shaft, the connection area and the handle thereby form a type of base body.
In this connection, the subject of DE 20 2004 017 974 U1 is based on surgical punching instruments according to DE 43 16 768 A1, DE 43 16 769 C1, DE 295 00 422 U1, U.S. Pat. Nos. 5,026,375, 5,273,519, 5,569,258 as well as WO 96/39 959.
In these bone punches or punching instruments, the restoring springs for the actuating lever have a leaf-spring configuration and act as restoring springs between the fixed handle and the actuating lever. Since the assembly and disassembly are difficult in these prior-art restoring spring systems, such restoring springs may make the handling of such a punching instrument or such a bone punch difficult, since these springs may weaken or may not apply the necessary restoring force to ensure a proper functioning of the punching instrument. Furthermore, these restoring springs cannot be readily removed from one another or from the respective handle or actuating lever to which they are fastened.
Based on these leaf spring configurations, a restoring spring in the form of a compression coil spring (axial compression spring), which is arranged and guided at least partially in a guide groove of the sliding surface of the punching slide by means of a guide pin axially passing through the restoring spring, is used in the subject of DE 20 2004 017 974 U1. A distal stop surface, which is rigidly connected to the punching slide, is provided as a step bearing for the rear distal spring end of the restoring spring. Furthermore, with its front proximal end in case of a removed punching slide, the restoring spring is in contact with a proximal stop surface of the punching slide. The restoring spring is in contact with a proximal stop surface of the guide shaft itself in the case of an ergonomically assembled punching slide.
This means that the restoring spring in this configuration is an integral component of the guide shaft and of the punching slide, so that it is not outwardly visible. When the punching slide is removed from the guide shaft, this restoring spring is automatically not operatively interacting, so that especially the assembly and disassembly of the punching slide on the guide shaft are considerably simplified.
However, it has been recently desired that after detaching the guide elements the punching slide can be separated from the base body consisting of the guide shaft, the connection area and the handle, but the punching slide and the base body still remain in connection with one another in some way, so that these two parts cannot be completely separated from one another and, for example, can be cleaned together. Since especially a plurality of bone punches shall be cleaned in a joint cleaning process, such a secure “securing” has the advantage that the components of a bone punch belonging together can always be correctly reassembled.
In this respect, a bone punch, called a surgical instrument, is known from DE 10 2009 056 099 B4, in which such a mode of operation is provided after separating the punching slide from the guide shaft or from the base body. This is achieved in this subject by the punching slide, in the position separated from the guide shaft, being arranged pivotably at the guide shaft. The guide shaft has, for this purpose, at its proximal end an elongated hole, in the area of which the punching slide has two side walls, which are spaced apart from one another laterally and protrude downwards to above the elongated hole and which are in connection with the mounting pin, which in turn extends through the elongated hole. In this case, this mounting pin is configured as a type of screw and is connected to the two side walls in a fixed manner. Provisions are thereby made for the guide shaft or the base body to have a reduced width in the area adjacent to the elongated hole so that the two side walls do not project laterally beyond the guide shaft or the connection area of the guide shaft to the handle.
In this configuration, the “securing means” are in the form of the elongated hole as well as of the two side walls with the securing pin freely accessible from outside, so that these may become contaminated. Furthermore, a special configuration of the connection area between the guide shaft and the handle is provided here, since this elongated hole must extend distally rearward over a considerable path of adjustment in the longitudinal direction of the guide shaft.